Effect of the surface conductance on electrokinetic potential measured in nonaqueous media

The effect of the surface conductance on the zeta -potential of dispersed p articles determined From their etectrophoretic mobility in nonaqueous elect rolyte solutions was considered. The conductivity of dilute quartz suspensi ons and the electrophoretic mobility of quartz particles in NaBr solutions in butanol-1 and dimethyl sulfoxide as well os in LiBr solutions in acetone at the salt concentration C = 10(-5)-10(-2) M were determined by conductom etry anti microelectrophoresis. The dependences of surface conductivity and zeta -potential on the electrolyte content were calculated bp formulas of the Wagner and Henry theories. It was shown that, in the region of dilute s olutions, zeta (log C) curves thus obtained significantly differ from corre sponding functions calculated by the Smoluchowski equation. At the same tim e, these dependences agreed closely with the zeta (log C) dependences deter mined for the same systems by the streaming potential method with allowance s for experimental values of the sui face conductivity. Using aluminum oxid e suspensions in NaBr and HBr ethanol solutions as examples, it was shown t hat, to obtain correct values of the zeta -potential from electrophoretic m obility of porous particles impregnated with a solution, it is necessary to allow for the bulk conductance of the particles.